Solvent of pyroxylin and compositions containing the same



UNITED STATES PATENT OFFICE.

EDMUND M. FLAHERTY, OF PARLIN, NEW JERSEY, ASSIGNOR TO E. I. DU PONT DE NEMOURS & COMPANY, OF WILMINGTON, DELAWARE, A CORPORATION OF DELAWARE.

SOLVENT OF PYROXYLIN AND COMPOSITIONS CONTAINING THE SAME.

N 0 Drawing.

To aZ Z whom it may concern.

Be it known that I, EDMUND M. FLAHERTY, of Parlin, in the'county of Middlesex and in the State of New Jersey, have invented a certain new and useful Improvement in Solvents of Pyroxylin and Compositions Containing the Same, and do hereby declare that the following is a full, clear, and exact description thereof.

The object of my invention is to provide a solvent for pyroxylin bodies having the qualities of being cheap, having high solvent power, being free from precipitation of pyroxylin, non-hygroscopic, adapted to form a very fluid but cohesive solution, and of pleasant odor.

A further objectis to use a solvent composition containing constituents which have approximately the same vapor tension, as it is desirable to have a number of the constituents evaporate more or less simultaneously.

A further object is to provide a solvent composition which,.by.reason of the presence of the particular alcohol therein, can be regulated as to its fluidity by varying the quantity of the alcohol as compared with the quantity of solid constituents therein.

In the pyroxylin industries, such as in the manufacture of lacquers, artificial leather, varnishes, etc., there is a demand for a sol-' vent having the above stated qualities.

-- None of the ordinary pyroxylin solvents,

such as glacial acetic acid, amyl acetate and acetone, including their homologues and derivatives, has all of these roperties in the highest degree, except per aps, amyl acelate, the price of which is very high. In

these several industries, it is desirable to vary the relative proportions of the solvent and pyroxylin to obtain a solution of the strength desired, according to the nature of the pyroxylin film to be formed. For example, in lacquer work the solution ordinarily does not contain over five ounces of pyroxylin per gallon in order that a film of proper thickness may be deposlted. In some of the decorative arts a very heavy film is employed, which can be deposited from a solution containing as high as twenty ounces of pyroxylin per gallon. There is, thus, for

each industry a strength of solution which is best adapted thereto. Where a solution Specification of Letters Patent.

amon

Application filed September 11,1918. Serial No. 253,525.

is desired having less pyroxylin than the total amount which the solvent is capable of taking up (for instance, if a solution of twenty ounces of p roxylin to a gallon of solvent were desired which is less than the total amount which the solvent would take up), it is unnecessary to have the entire quantity of solution composed of pure solvent, it only being necessary to have enough solvent present ,to dissolve the desired amount of pyroxylin. For economy, therefore, it is customary to add cheap diluents to the solvent, which diluents are either entirely non-solvent or nearly so. Ihe use of diluents, however, introduces difficulties,

which may be mentioned the following: when, as used in a factory, these solvents are evaporated at the ordinary room atmosphere in order to deposit a film of pyroxylin, there is a tendency, except in the case of those solvents which are non-hygroscopic but expensive, such as amyl acetate, toward a separation out of the nitrocellulose or other solvents throu h absorption of moisture from the air or t rough the change in the composition of the solvent mixture resulting from the unequal rate of evaporation of its components, this precipitation being usually evidenced by the appearance of a whitish substance, technically known as blushing or blooming, or by the settling to the bottom of a jellylike mass. Such separation tends to decrease the strength of the film, and, in some cases, the white appearance produces objectionable color efi'ects.

I have discovered that by using a mixture of normal butyl acetate with an alcohol of the paraffin series and a hydrocarbon of the benzene series, or benzin, a mixture is obtained, which has highsolvent powers for pyroxylin, is comparatively non-hygroscopic, and upon evaporation deposits a strong, smooth, transparent film.

Normal butyl acetate is better than is butyl acetate in pyroxylin mixtures as it evaporates more slowly and, therefore, deposits a smoother film and is more resistent to humidity.

For example, my invention may be carried out by using a solvent mixture comprised of 40% by weight of normal butyl acetate and by weight of benzene or benzin, or instead, I may use a solvent mixture comprising ll parts by Weight of normal butyl acetate, 50 parts by Weight of benzene or benzin and 9 parts of normal butyl alcohol, said solvent mixture having dissolved therein a quantity of nitrocellulose in the proportion of 2 pounds of nitrocellulose to 7 pounds of the solvent mixture. But the relative percentages of these ingredients may vary Widely according t0! the conditions covering the innumerable uses to which the solution mziy be put.

have given specific instances merely by way of illustration, and am not to be confined to the particular proportions given, as they are to be regarded as typical only.

An increase in the hydrocarbon component results in reduced cost and its disadvantage lies in the less rapid solvent action which such a mixture possesses.

The fluidity can be varied by varying the quantity of the alcohol.

Numerous other substances, such as other pyroxylin solvents, oil, pigments, gums, resins, etc., may be added to the pyroxylin mixture, each having its own properties, and these properties will of course, aflect the properties of the final mixture, but the general principle Will still obtain.

While I have described my invention above in detail, I wish it to be understood that many changes may be made therein Without departing from the spirit of the invention.

Claims:

1. A solvent comprising a mixture of normal butyl acetate and a hydrocarbon.

the parafiin series.

2. A solvent comprising a mixture of normal butyl acetate and benzin.

3. A solvent comprising a mixture of normal butyl acetate, a hydrocarbon and an alcohol of the parafiin series.

l. A solvent comprising a mixture of normal butyl acetate, benzin and an alcohol of 5. A solvent comprising a mixture of normal butyl acetate, benzin and normal butyl alcohol. v

6. A composition comprising pyroxylin, and a solvent comprising a mixture of normal buty-l acetate and a hydrocarbon.

7. A composition comprising pyroxylin, and a solvent comprising a mixture of nor mal butyl acetate and benzin.

8. A composition comprising pyroxylin, and a solvent comprising a mixture of nor mal 4 butyl acetate, a hydrocarbon and an alcohol of the paraffin series.

9. A composition comprising pyroxylin,

. and a solvent comprising a mixture of normal butyl acetate, benzin and an alcohol of the paraffin series.

10. A composition comprising pyroxylin, and a solvent comprising a mixture of normal butyl acetate, benz'in and normal butyl alcohol.

In testimony that I claim the foregoing I have hereunto set my hand.

EDMUND M. FLAHERTY.

Witnesses:

H. N. WILSON, MARY PETERSEN. 

